Apparatus for making window envelopes

Abstract

Disclosed are a method and an apparatus designed to make a window envelope rapidly using a water-soluble clarifying agent without causing an inconvenience in its window area. Upstream of an envelope making stage wherein a continuous paper while traveling along a continuous path of travel is successively folded, pasted and cut to form an envelope, a water-soluble clarifying agent is applied to an area on the continuous paper that is designed to become the transparent window in the envelope and the continuous paper carrying the clarifying agent is wound on a plurality of drying cylinders so that its surface carrying the clarifying agent faces outwards to dry the clarifying agent while holding the surface of paper carrying the clarifying agent out of contact with the drying cylinders.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a method of and an apparatus for making window envelopes in which a clarifying agent is applied to a portion of paper making up an envelope to provide the envelope with a transparent window. The term “clarifying agent” is used herein to refer to a chemical agent which when applied to or carried in a part of paper acts to make that part of paper transparent.[0003]2. Description of the Prior Art[0004]While various types of the clarifying agent used to make a window portion of a paper envelope transparent have been proposed, it is desired that they be water-soluble together with the paper forming the envelope to allow such window envelopes after use to be recycled. For example, as described in JP H08-284097 A there is used a water-soluble clarifying agent in which 0 to 1.0 part by weight of silicone antifoaming or die-release agent and 0 to 20 parts by weight in active ingredient of a wax e...

AI Technical Summary

Benefits of technology

Ensures the clarifying agent is fully dried before reaching the envelope forming stage, preventing mottling and allowing for efficient recycling, while maintaining high productivity.

Problems solved by technology

A clarifying agent to permit recycling must be water-soluble as mentioned above but as such is not much good in drying characteristics as those of UV curing type.

Paper having a water-soluble clarifying agent applied thereto may, therefore, have to be passed over a roller while the clarifying agent has not enough been dried yet, and it is then very likely that parts of the undried solution upon contacting the roller are scraped off the paper, thereby mottling the window potion formed on the paper.

Preventing this possibility requires the continuous paper carrying the clarifying agent to be slowed down in its rate of travel, but this then brings about inferiority in productivity of window envelopes.

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